1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
|
use crate::{
app::AppState,
lisp::{
error::{EvalError, LispError},
expr::{Arity, Ident, LispExpr, LispFunction},
Environment,
},
type_match,
};
use std::convert::TryInto;
use log::{error, info};
pub type Context = Vec<String>;
pub struct Evaluator<'ctx, 'global> {
pub app: &'global mut AppState<'ctx>,
pub context: Context,
}
impl<'ctx, 'global> Evaluator<'ctx, 'global>
where
'ctx: 'global,
{
pub fn eval(&mut self, expr: &LispExpr) -> Result<LispExpr, LispError> {
match expr {
LispExpr::Unit => Ok(expr.clone()),
LispExpr::StringLit(_) => Ok(expr.clone()),
LispExpr::Char(_) => Ok(expr.clone()),
LispExpr::Number(_) => Ok(expr.clone()),
LispExpr::BoolLit(_) => Ok(expr.clone()),
LispExpr::Ident(ref id) => lookup(&self.app.lisp_env, id),
LispExpr::Quote(_, _) => Ok(expr.clone()),
LispExpr::List(li) => {
let func_expr = &li[0];
match func_expr {
LispExpr::Ident(s) => match s.as_ref() {
"define" => self.define_var(&li[1..]),
"set!" => self.set_var(&li[1..]),
"lambda" => create_lambda(&li[1..]),
"if" => self.eval_if(&li[1..]),
"cond" => self.eval_cond(&li[1..]),
"quote" => quote_var(&li[1..]),
_ => {
let mut new_ls = vec![self.eval(&func_expr)?];
new_ls.extend(li[1..].to_vec());
self.eval(&(LispExpr::List(new_ls)))
}
},
LispExpr::PrimitiveFunc(f) => {
let mut args = Vec::new();
// context.push(f.name.to_string());
for item in li[1..].iter() {
args.push(self.eval(item)?);
}
f.call(&args, &mut self.app)
}
LispExpr::Function(f) => {
let mut args = Vec::new();
for item in li[1..].iter() {
let i = self.eval(item)?;
args.push(i);
}
if f.params.len() != args.len() {
info!("too many or too little number of args");
Err(EvalError::ArgumentCount(Arity::Exact(f.params.len())).into())
} else {
let nested_env: Environment =
f.params.clone().into_iter().zip(args).collect();
self.app.lisp_env.push(nested_env);
let result = if f.body.is_empty() {
Ok(LispExpr::Unit)
} else {
self.eval(&LispExpr::List(f.body.clone()))
};
self.app.lisp_env.pop();
return result;
}
}
LispExpr::List(_) => {
info!("list as funciton");
let func_expr = self.eval(&func_expr)?;
let mut new_ls = vec![func_expr];
new_ls.extend(li[1..].to_vec());
self.eval(&(LispExpr::List(new_ls)))
}
_ => Err(EvalError::BadForm.into()),
}
}
_ => Err(EvalError::BadForm.into()),
}
}
pub fn define_var(&mut self, args: &[LispExpr]) -> Result<LispExpr, LispError> {
let arity = Arity::Exact(2);
if !arity.check(args) {
return Err(arity.to_error());
}
match args {
[LispExpr::Ident(id), expr] => {
let value = self.eval(&expr)?;
let local_env = &mut self.app.lisp_env.last_mut();
if let Some(env) = local_env {
env.insert(id.into(), value);
} else {
error!("Unable to create global definition");
return Err(EvalError::BadForm.into());
}
return Ok(LispExpr::Unit);
}
[LispExpr::List(shorthand), LispExpr::List(body)] => {
// (define (func arg) <body>) shorthand
let id = shorthand[0].unwrap_ident();
let params = if shorthand.len() > 1 {
&shorthand[1..]
} else {
&[]
}
.to_vec()
.into_iter()
.map(|arg| arg.try_into())
.collect::<Result<Vec<Ident>, LispError>>()?;
let value = LispExpr::Function(LispFunction {
params,
body: body.to_vec(),
});
let local_env = &mut self.app.lisp_env.last_mut();
if let Some(env) = local_env {
env.insert(id.into(), value);
} else {
error!("Unable to create global definition");
return Err(EvalError::BadForm.into());
}
return Ok(LispExpr::Unit);
}
_ => {
error!("Invalid usage of `define`");
Err(EvalError::BadForm.into())
}
}
}
pub fn set_var(&mut self, args: &[LispExpr]) -> Result<LispExpr, LispError> {
let arity = Arity::Exact(2);
if !arity.check(args) {
return Err(arity.to_error());
}
match args {
[LispExpr::Ident(id), expr] => {
let value = self.eval(&expr)?;
let local_env = self.app.lisp_env.last_mut();
if let Some(env) = local_env {
return env
.insert(id.into(), value)
.ok_or(EvalError::UnboundVariable(id.into()).into());
} else {
error!("Unable to set in global env!");
return Err(EvalError::BadForm.into());
}
}
_ => {
error!("Invalid usage of `set!`");
return Err(EvalError::BadForm.into());
}
}
}
pub fn eval_if(&mut self, args: &[LispExpr]) -> Result<LispExpr, LispError> {
let arity = Arity::Exact(3);
if !arity.check(args) {
return Err(arity.to_error());
} else {
match args {
[predicate, then, else_] => {
let predicate = self.eval(&predicate)?;
if matches!(predicate, LispExpr::BoolLit(false)) {
return self.eval(&else_);
} else {
return self.eval(&then);
}
}
_ => {
panic!("panicked at `if` expression")
}
}
}
}
pub fn eval_cond(&mut self, args: &[LispExpr]) -> Result<LispExpr, LispError> {
let arity = Arity::Atleast(1);
let valid_cond_stmt = |expr: &LispExpr| matches!(expr, LispExpr::List(v) if v.len() == 2);
if !arity.check(args) {
return Err(arity.to_error());
} else {
for cond_stmt in args {
if valid_cond_stmt(cond_stmt) {
match &cond_stmt.unwrap_list()[..] {
[predicate, then] => {
if self.eval(&predicate)?.cast_bool() {
return self.eval(&then);
}
}
_ => return Err(EvalError::BadForm.into()),
}
} else {
error!("bad `cond` form");
return Err(EvalError::BadForm.into());
}
}
return Ok(LispExpr::Unit);
}
}
}
pub fn quote_var(args: &[LispExpr]) -> Result<LispExpr, LispError> {
let arity = Arity::Exact(1);
if !arity.check(args) {
return Err(arity.to_error());
} else {
return Ok(args[0].clone().quote(1));
}
}
pub fn create_lambda(cdr: &[LispExpr]) -> Result<LispExpr, LispError> {
let arity: Arity = Arity::Exact(2);
if !arity.check(cdr) {
return Err(arity.to_error());
}
match cdr {
[LispExpr::List(params), LispExpr::List(body)] if type_match!(params, (..) => LispExpr::Ident(_)) =>
{
return Ok(LispExpr::Function(LispFunction {
params: params
.into_iter()
.map(|p| p.unwrap_ident())
.collect::<Vec<_>>(),
body: body.clone(),
}));
}
_ => {
error!("Invalid usage of `lambda`");
return Err(EvalError::BadForm.into());
}
}
}
pub fn lookup(env_list: &[Environment], key: &str) -> Result<LispExpr, LispError> {
if env_list.is_empty() {
return Err(EvalError::UnboundVariable(key.into()).into());
} else {
let local_env = env_list.last().unwrap();
if let Some(val) = local_env.get(key) {
return Ok(val.clone());
} else {
return lookup(&env_list[..env_list.len() - 1], key);
}
}
}
#[cfg(test)]
mod tests {
use super::*;
use crate::lisp::{expr::LispExpr, lex::Lexer, number::LispNumber, parse::Parser};
fn run(code: &str, app: &mut AppState) -> LispExpr {
let mut parser = Parser::new(Lexer::new(code, 0));
let mut evaluator = Evaluator {
app,
context: Vec::new(),
};
evaluator
.eval(&parser.parse_single_expr().unwrap())
.unwrap()
}
#[test]
fn eval_all() {
let sdl_context = sdl2::init().unwrap();
let ttf_context = sdl2::ttf::init().unwrap();
let mut app = AppState::init(100, 100, &sdl_context, &ttf_context, None, None).unwrap();
eval_arithmetic(&mut app);
eval_logical(&mut app);
eval_quote(&mut app);
}
fn eval_arithmetic(app: &mut AppState) {
assert_eq!(
run("(+ 1 2 3)", app),
LispExpr::Number(LispNumber::Integer(6))
);
assert_eq!(
run("(+ 1.1 2.2 3.3)", app),
LispExpr::Number(LispNumber::Float(6.6))
);
assert_eq!(
run("(* 1 2 3 4 5)", app),
LispExpr::Number(LispNumber::Integer(120))
);
assert_eq!(run("(< 1 2)", app), LispExpr::BoolLit(true));
assert_eq!(run("(> 6 5 4 3 2 1)", app), LispExpr::BoolLit(true));
assert_eq!(run("(< 1 2 3 4 5 6)", app), LispExpr::BoolLit(true));
assert_eq!(run("(>= 5 5 4 3 2 1)", app), LispExpr::BoolLit(true));
assert_eq!(run("(<= 2 2 3 4 5 6)", app), LispExpr::BoolLit(true));
}
fn eval_quote(app: &mut AppState) {
assert!(run("(quote a)", app).cast_bool());
assert!(run("(eq? 'a 'a)", app).cast_bool());
assert!(run("(eq? '(1 2 3) '(1 2 3))", app).cast_bool());
assert!(run("(eq? '(1 '(1 2 3)) '(1 '(1 2 3)))", app).cast_bool(),);
assert!(run("(eq? '#t '#t)", app).cast_bool());
}
fn eval_logical(app: &mut AppState) {
assert!(run("(and #t #t)", app).cast_bool());
assert!(run("(or #f #t)", app).cast_bool());
assert!(run("(not #t)", app).cast_bool());
assert_eq!(run("(not #f)", app), run("(not (not #t))", app));
}
}
|